Effect of fertilizer application on growth and yield of soybean variety vnuad2 in winter season 2021 (khóa luận tốt nghiệp)

27 4.2 Effects of fertilizers on fresh weight of VNUAD2 variety in winter season 2021 at different growth stages .... Effects of fertilizer on dry weight of VNUAD2 variety in winter sea

VIETNAM NATIONAL UNIVERSITY OF AGRICULTURE

VNUAD2 IN WINTER SEASON 2021

Supervisor: Senior lecturer, Dr VU THI THUY HANG

Department: PLANT GENETICS AND BREEDING

HA NOI – March, 2021

DECLARATION

I hereby declare that this paper is my own work All results and data in this thesis are absolutely honest and have not been submitted before to any institution for assessment purposes All sources used in this paper were cited in references

Student

Lê Đức Hiền

ACKNOWLEDGEMENT

To complete this thesis, I am deeply indebted to people who have been

providing me with precious support and advice

Firstly, I would like to send my gratitude to my supervisor, Dr Vu Thi Thuy Hang, Department of Plant Genetics and Breeding, Faculty of Agronomy, Vietnam National University of Agriculture, for her enthusiastic support, helpful

advice and considerable encouragement in the completion of my thesis

I would also like to express sincere thanks to the lecturers from the Faculty of Agronomy in general and lecturers in the Department of Plant Genetics and Breeding in particular, who taught and created best conditions for

students during learning process and research

I would like to give special thanks to Dr Vu Ngoc Thang, Ms Phạm Thị

Ly and Mr Hoàng Đức Nhật Linh for their helpful technical supports

Last but not least, I want to express my sincere thanks to my family and friends who have always been by my side, give me support and strength to

complete this graduation thesis

TABLE OF CONTENTS

DECLARATION i

ACKNOWLEDGEMENT ii

TABLE OF CONTENTS iii

LIST OF TABLES v

LIST OF FIGURES vi

ABSTRACT vii

CHAPTER 1 INTRODUCTION 1

1.1 Background 1

1.2 Objective and requirements 2

1.2.1 Objective 2

1.2.2 Requirements 2

PART II: LITERATURE REVIEW 3

2.1 Classification, origin of soybean 3

2.1.1 Origin of soybean 3

2.1.2 Classification of soybean 4

2.2 Soybean production in the world 4

2.3 Soybean production in Vietnam 8

2.4 Values of soybean 11

2.5 Fertilizer application in soybean production 12

2.5.1 General principles of fertilizer application 12

2.5.2 Research on fertilizer application for soybean in the world 14

2.5.3 Research on fertilizer application for soybean in Vietnam 17

CHAPTER III MATERIALS AND METHOD 21

3.1 Plant materials 21

3.2 Location and time 21

3.3 Experimental design 21

3.4 Cultural practices 23

3.5 Trait measurements 23

3.5.1 Growth and development characters 23

3.5.2 Yield components and yield 25

3.6 Evaluation of disease and pest damage and lodging resistance of VNUAD2 25

3.7 Data analysis 26

CHAPTER 4 RESULTS AND DISCUSSION 27

4.1 Effects of fertilizers on growth of VNUAD2 variety in winter season 2021 27

4.2 Effects of fertilizers on fresh weight of VNUAD2 variety in winter season 2021 at different growth stages 29

4.3 Effects of fertilizer on dry weight of VNUAD2 variety in winter season 2021 at different growth stages 34

4.4 Effects of fertilizers on nodule formation of VNUAD2 variety in winter season 2021 at different growth stages 38

4.5 Effects of fertilizer on leaf area and leaf area index of VNUAD2 variety in winter season 2021 at different growth stages 41

4.6 Effects of fertilizers on yield components of VNUAD2 variety in winter season 2021 43

4.7 Effect of fertilizers on individual yield and yield of VNUAD2 variety in winter season 2021 47

4.8 Effects of fertilizers on disease, pest damage and lodging resistance of VNUAD2 variety in winter season 2021 49

CHAPTER 5 CONCLUSIONS AND SUGGESTIONS 51

5.1 Conclusions 51

5.2 Suggestion 51

REFERENCES 52

A Vietnamese references: 52

B Foreign references: 53

SOME PICTURES ABOUT PROCESS CONDUCTED UNDERGRADUATE THESIS 55

LIST OF TABLES

Table 2.1 Status of soybean production in the world in the period

2010-2020 5 Table 2.2 Area, yield and production of soybeans of some countries in the

period 2015-2020 7 Table 2.3 Area, yield and production of soybean in Vietnam during 2010-

2020 9

Table 3.1 Measured traits for VNUAD2 in winter season 2021 24

Table 3.2 Yield components and yield measurement for VNUAD2 in winter

season 2021 25 Table 3.3 Evaluation of disease and pest damage and lodging resistance of

soybean 26 Table 4.1 Effects of fertilizers on growth of VNUAD2 variety in winter

season 2021 28 Table 4.2 Effects of fertilizers on fresh weight of VNUAD2 variety in

winter season 2021 at different growth stages 31 Table 4.3 Effects of fertilizer on dry weight of VNUAD2 variety in winter

season 2021 at different growth stages 35 Table 4.4 Effects of fertilizer on nodules of VNUAD2 variety in winter

season 2021 at different growth stages 39 Table 4.5 Effects of fertilizer on leaf area and leaf area index (LAI) of

VNUAD2 variety in winter season 2021 at different growth stages 42 Table 4.6 Effects of fertilizers on yield components of VNUAD2 variety in

winter season 2021 45 Table 4.7 Effects of fertilizers on individual yield and yield of VNUAD2

variety in winter season 2021 48 Table 4.8 Effects of fertilizers on disease, pest damage and lodging

resistance of VNUAD2 variety in winter season 2021 49

LIST OF FIGURES

Figure 4.1 Growth of VNUAD2 at different fertilizer treatment at podding

stage 33 Figure 4.2 Nodule formation of VNUAD2 at different fertilizer treatment 41

ABSTRACT

This study aimed to identify the most suitable levels of nitrogen and potassium fertilizers for growth and yield of soybean variety VNUAD2 The experiment design split plot design with 3 replications Three levels of nitrogen (40, 50 and 60 kg/ha) and four levels of potassium (60, 80, 100 and 120 kg/ha) were applied Plant density was of 50 plants/m², with 2 rows/plot and plot size

of first pod insertion, number of leaves, nodes and primary branches on main stem, dry and fresh weight of plants, nodule formation, yield components and

yield Pest and disease resistance and lodging resistance were also recorded

Results showed that the growth parameters were affected by different fertilizer rates The amount of nitrogen at the level of 50 kg/ha and the amount

of potassium at the level of 100 kg/ha resulted in higher plant height, first pod insert height, number of nodes, number of leaves, and number of primary branches Different rates of nitrogen and potassium also affect fresh and dry weight stem and roots, nodule characters and leaf areas at different growth stages The level of 50 kg/ha of nitrogen and 100 kg/ha of potassium provided the higher values than other rates Besides, the leaf area and leaf area index reached the high values at the application of 60 kg/ha of nitrogen and 80 kg/ha

of potassium at the fruiting stage Yield components were also affected by different rates of fertilizer application Individual yield and yield achieved significantly high values when fertilizer was applied at 50 kg/ha for nitrogen and

at 100 kg/ha for potassium

CHAPTER 1 INTRODUCTION 1.1 Background

Soybean (Glycine max (L) Merrill) is a short-term industrial crop with multi-faceted effects It is a plant of high economic value, occupies an important position in the transformation of crop structure and diversity agricultural products in our country towards commodity agricultural production and sustainable agricultural development In addition, soybean is also a plant with the ability to fix nitrogen, increase soil fertility, and improve soil very well Its products are a source of food for humans, animal feed, raw materials for the processing industry, and valuable export items Therefore, soybean cultivation has long been interesting and strongly developed in many countries around the world, including Vietnam (Duong Hong Dat, 2012)

use as food, animal feed, and industrial material, with seeds being characterized

by a high content of protein (30 – 48%) and oil (13 – 22%) Soybean is ranked number one in the world oil production (48%) in the international trade markets among the major crops, including cottonseed, peanut, sunflower seed, coconut and palm kernel (Singh and Hymowitz 1999) In addition, soybean, as other legume plays a critical and important role in ecosystems and sustainable agriculture because of its ability to sequester C while enhancing soil quality and tilth (Graham and Vance 2003) Its capacity for symbiotic nitrogen fixation with compatible rhizobia (Graham and Vance 2003) provides essential and „free‟ nitrogen for use by the host plants or by associated or subsequent crops

Soybean was domesticated from wild soybean, Glycine soja Sieb

et Zucc in the cool, humid north-east of China (Hymowitz 1970) Then, the soybean was disseminated to other Asian countries such as Korea, Japan, Indonesia, the Philippines, India, Thailand, and Vietnam By the 16th and 17th centuries, the soybean was introduced to Europe and North America (Singh and

Hymowitz 1999) Since the crop improvements aimed soybean as a grain crop started in the 1920s in well- irrigated areas of United States, soybean has become a large commercial grain crop and has been breed for mechanized agriculture (Hymowitz 1988) Nowadays, the soybean is a world crop, cultivated widely in the USA, Brazil, Argentina, China and India

Soybean production is affected by many factors including varieties, agronomic practices, and climate conditions Of which, agronomical practices such as plant density, sowing time and fertilizer application are need to be studied to find the most suitable practice for any new varieties VNUAD2 is a new soybean variety and its plant density of 40 – 50 plant/m2 was identified by

Vu et al (2021) However, there have not been studies on fertilizer application for it Therefore, we conduct the “Effect of fertilizer application on growth and yield of soybean variety VNUAD2.”

1.2 Objective and requirements

- Agronomical traits related to growth and development of VNUAD2 under different fertilizer application treatments

- Yield components and yield of VNUAD2 under different fertilizer application

- Based on growth performance and yield of VNUAD2 to select the most suitable level of fertilizer application

PART II: LITERATURE REVIEW

2.1 Classification, origin of soybean

2.1.1 Origin of soybean

The soybean (Glycine max (L) Merr.) is believed to be one of the oldest

food crops in the world Some evidences that relate to history, geography and archaeology all indicate that soybeans are native to Asia and originated in

China The soybean was domesticated from its wild ancestor (called Glycine

soja) which was distributed throughout China, Japan, Korea, East Asia but its

distribution in China is most extensive the largest (Qiu and Chang, 2010) Based

on historical observations, both Fukuda (1933) and Hymowitz (1970) thought that Northeast of China was the origin of soybean because various semi-wild soybeans were distributed there and many soybean varieties carried primary features in this region However, many other theories are that soybean is

originated from the south of China (Wang, 1947; Ding et al., 2008) or from

other areas in China (Lu, 1978)

immense economic values of soybeans were really approved in the 1920s Only when considered as seed crops and cultivated in favorable irrigation areas in the

US, has soybean become such a crop with great commercial values and selected for mechanized agriculture (Hymowitz, 1988)

Some studies documented that soybean was cultivated in Vietnam during

Hung dynasty and even earlier than mung bean and black bean (Ngo The Dan et

al., 1999) Despite its very early appearance, soybean has been developed as a

potential crop with high nutrition values and made a great contribution to Vietnam‟s economy over a few decades However, both soybean cultivation area and productivity are still much lower than these of other countries in the world

Nowadays, Vietnam still imports a large quantity of soybean and its processed products from US, China and other countries

2.1.2 Classification of soybean

Soybean is polyploidy origin due to high chromosome number; it includes

diploid and tetraploid nature (2n = 40 or 4n = 40) in the family Leguminosae, the subfamily Papilionoideae, the tribe Phaseoleae and the genus Glycine and, scientific name is Glycine max (L.) Merrill

There are many different classifications, but so far, the system of classification was mainly relied on morphological characteristics, geographical distribution and the number of chromosomes

Glycine genus is subdivided into 26 perennial wild indigenous species of

Australia with perennial crops in Australia, the South Pacific Island, the Philippines, Taiwan and Southeast China The genomes of 2n, 4n genes and multiple deflates (40, 80, 38, 78) (Chung and Singh, 2008; Orf, 2010) Hybridisation between the species in this sub-family is very unsuccessful,

except for Glycine canescense grown for animal feed Thus, in vitro culture in

pre-embryo stage will be obtained in order to obtain some ripening fruit between

the diploid species of this subspecies and Glycine max Some crosses between

G max and tetraploid species, G tomentella, can produce hybrid and F1 seeds,

but the F1 plants are ineffective (Nguyen Van Hien, 2000)

The areas where soybeans are mainly grown range from cold climate regions (Northern U.S and Canada) to tropical regions (Indonesia) Temperatures between 22 and 35°C are required for its growing season, and can affect its flowering dates

temperate-2.2 Soybean production in the world

Soybeans are the most important oilseed crops in the world, ranking fourth after wheat, rice and maize Due to its wide adaptability, it has been cultivated in about 70 countries but is concentrated in the Americas more than

70%, followed by Asia (Hartman et al., 2016) Currently, soybean genetic resources in the world are stored mainly in 15 countries including Taiwan, Australia, China, France, Nigeria, India, Indonesia, Japan, Korea, South Africa, Sweden, Thailand, USA and Russia with 45,038 varieties (Tran Dinh Long, 2002)

Soybean production situation in the world in recent years is shown in table 2.1

Table 2.1 Status of soybean production in the world in the period

2010-2020

(million ha)

Yield (ton/ha)

Production quantity (million ton)

(Source: Faostat, 2021; https://apps.fas.usda.gov/psdonline/circulars/production.pdf)

Soybean production in the world has increased significantly over the years The area from 102.8 million hectares (2010) increased to 122.4 million hectares (2019), an increase of 19.6 million hectares The yield increases substantially from 2.6 tons/ha (2010) and to 2.8 tons/ha (2019) During the years

2010 - 2019, the production quantity tends to increase over years due to increased acreage and productivity with almost 265.1 million ha in 2010 and 336.6 million ha in 2020 In recent years, the demand for products made from

soybean is increasing but the world soybean production area is decreasing Perhaps the cause is an outbreak of some animal diseases and a reduction in the need for raw materials for animal feed, especially in China

Forecast in 2020, the area for soybean in the world was 127.6 million ha, the yield was 2.9 ton/ha and production were 368.5 million tons The largest areas of soybean production in the world are in the Americas, followed by Asia, Europe and Africa The Americas provides 87.1% of global soybean production

America, Brazil, Argentina, India, and China are the leading countries in soybean production and their soybean production accounts for 90-95% of the world production Among major producing countries, the Brazil is the top producer during the year 2015-2020, (38.6 million ha and 133.0 tons) in terms of area and production in 2020, followed by USA (33.3million ha and 116.2 tons), Argentina (17.3 million ha and 53.5 tons) and China (9.3million ha and 17.5 tons), respectively (Table 2.2) This is the result of the application of techniques, mechanization in agricultural production, high yield transgenic and pest resistance varieties In addition, in the development strategy, countries also increase the soybean acreage by replacing other crops such as sunflower (in Argentina), cotton (in the US), using grasslands (in Argentina and Brazil) or replacing native plants (in Brazil) (Masuda and Goldsmith, 2009)

Table 2.2 Area, yield and production of soybeans of some countries in the

(Source: Faostat, 2021; https://apps.fas.usda.gov/psdonline/circulars/production.pdf)

Due to the selection methods, mutagenicity and hybrid, the United States has created and breeding new soybean varieties Varieties with high yield used

as breeding sources in breeding programs Studies in soybean breeding by mutant methods in the United States also achieved many results Especially after many years of testing thousands of soybean varieties, the United States has

found soybean allergy-free varieties Today, most of development of soybean varieties are conducted by private sector However, public-sector breeders still have an important role In addition to variety development, public sector breeders place emphasis on germplasm enhancement, breeding methodology and molecular technology development In the future, the productivity of modern agriculture will depend largely on the ability to breed new varieties adaptable to changing environmental conditions and management strategies

China is a neighboring country of Vietnam and has similar farming practices Currently, China is the 4th largest country in the world in soybean production China has applied scientific advances in hybrid and imported varieties In addition, China has a number of programs to improve soybean varieties with resistance to pests and weeds, suitable to the sub-regional climate These typical varieties are CN001, CN002 and YAT12 In recent years, China has also developed many new varieties by mutation such as Tiefeng 18 resistant

to high alum, good lodging resistance, high productivity and good quality (Ngo The Dan, 1994)

In general, the world's soybean production in recent years has thrived due

to its nutritional and economic value The increase in yield and yield of soybeans was due to several factors, the most influencing being variety Forecasts also show that the annual world soybean production will increase by 2.2% to about 371.3 million tons by 2030 However, the reality shows that the production or demand for soybeans increases but the area of cultivated land seems to decrease That requires investment in research to improve seed yield (Masuda and Goldsmith, 2009)

2.3 Soybean production in Vietnam

Soybean was grown in Vietnam very early and used to process for familiar products such as soy sauce, tofu, cooking oil

Soybean planting area in our country reached the highest level in 2010 and decreased year by year (Table 2.3) If in 2010, our country's soybean growing area still reached 197.8 thousand hectares, then by 2017 it was only 68.5 thousand hectares, down 65.4% compared to 2010 Therefore, the annual soybean production 2017 was only 101.7 thousand tons, down 65.9% compared

to 2010 (298.6 thousand tons) Thus, although the average soybean yield in our country is relatively stable at about 15 quintals/ha, it is only approximately 1/2

of that of the world and the country's total soybean production can only meet 1/10 domestic soybean demand This means that we have had to import a large amount of soybeans over the years In 2014 we imported 1,564 thousand tons, worth 913.2 million USD, preliminary to August 2017 we imported 918.72 thousand tons, worth 391.93 million USD, the purpose is to serve feed processing industry, a very small part of which is used to process daily feed products such as milk, tofu or cooking oil (General Department of Customs, 2018)

Table 2.3 Area, yield and production of soybean in Vietnam during

In 2012, the soybean growing area of our country was 119.2 thousand hectares, decreasing gradually over the years By 2020, the area will be reduced

to 41.60 thousand hectares, a decrease of 65.10% compared to 2012

In 2012, the average yield of the whole country reached 1.45 tons/ha, increased continuously over the years and reached the highest level in 2016 at 1.61 tons/ha, then tended to decrease slightly over the years By 2020, our country's soybean yield will reach 1.57 tons/ha

Due to the gradual decrease in area and productivity, our country's soybean production has also decreased over the years In 2012, the total soybean production of the country reached 173.5 thousand tons By 2016 it will decrease

to 160.7 thousand tons and soybean production will decrease the most in 2020 at 65.4 thousand tons

According to Pham Dong Quang et al (2005), currently, soybeans are grown mainly in 27 provinces According to statistics, soybean growing area is mainly in the Northern provinces, about 100 thousand hectares (accounting for more than 80% of the total area of the country) More than 60% of soybeans are grown in highland areas The Northern Midlands and Mountainous region have the largest soybean growing area in the country with 49.7 thousand hectares (accounting for 45.1% of the total area of the country) and the production is 62.2 thousand tons (accounting for 39.4% of the total area of the country) Next is the Red River Delta with the second-largest soybean area, accounting for 36.5% of the total area (40.2 thousand ha) but the leading products in the country, accounting for 40.2% of the total production (63.5 thousand tons)

Vietnam is ranked 6th in soybean production in Asia (after China, India, Indonesia, Korea and Thailand) Over 40% of our country's soybean products are used to produce vegetable oil, the rest is used for human food, animal feed processing and breeding Currently, Vietnam's soybean production only meets more than 10% of domestic demand Therefore, for many years, our country has

had to import soybeans in large quantities and most of them are used for the purpose of processing animal feed

2.4 Values of soybean

Soybean is a short-term crop with high economic value It is hard to find a plant that is as multifaceted as soybean Its products are used as food for humans, feed for livestock, raw materials for the processing industry, export goods and as a soil improvement crop

- Food value: Soybean seeds have high nutritional content, average protein content is about 40-50%, lipid is 13-24%, carbohydrate is 22-35% In soybean seeds, there are quite a lot of vitamins, especially vitamin B1 and B2 content, in addition, there are vitamins PP, A, E, K, D, C Especially in germinating soybean seeds The amount of vitamins has increased much, especially vitamin C Currently, from soybean seeds, people have processed over 600 different products, of which more than 300 types of food are processed

by both ancient methods Traditional, handcrafted and modern forms of fresh, dried and fermented such as bean sprouts, tofu, soy sauce, soy sauce to other premium products such as coffee beans, confectionery and meat fillings Soybean is also a medicine to cure diseases, especially black soybean, which has good effects on the heart, liver, kidneys, stomach and intestines Soybean is a good food for people with diabetes, rheumatism, nervous breakdown and malnutrition

- Industrial value: Soybean is the raw material of many different industries such as processing artificial rubber, paint, printing ink, soap, plastic, rayon, liquid fuel, lubricating oil lubricants in the aviation industry, but mainly soybeans are used for pressing oil Currently in the world soybean is the leading plant providing raw materials for oil pressing, soybean oil accounts for 50% of the total amount of vegetable oil Characteristics of soybean oil: slow drying, high iodine index: 120-127; Condensation at temperature: -15 to -18oC From

this oil people make hundreds of other industrial products such as candles, soap, nylon

- Agricultural values:

+ As fodder for livestock: Soybean is a good source of fodder for livestock 1 kg of pea is equivalent to 1.38 units of animal feed The whole soybean plant (stem, leaves, fruit, seeds) has a high protein content, so by- products such as fresh leaves and stems can be very good fodder for livestock,

or dried as a general feed for livestock cattle Industrial by-products such as oilseed meals have quite high nutritional content: N: 6.2%, P2O5: 0.7%, K2O: 2.4%, so they make very good fodder for livestock (Ngo The Dan et al., 1999)

+ Soil improvement: soybean plants have the ability to fix atmospheric nitrogen through root nodules Soybean roots are deeply branched, making the soil porous Soybean is a valuable crop for soil improvement Soybean leaves are very good for making green manure In the humid tropical conditions of our country, soybean is a short-term crop that is easy to put into the system of crop rotation, increased cropping, and intercropping It is the first plant that gives the effect to the next plant

2.5 Fertilizer application in soybean production

2.5.1 General principles of fertilizer application

Fertilizer is an important factor determining the yield of crops Therefore,

it is necessary to have a basis for reasonable fertilization to achieve the highest yield In addition to determining the nutritional needs of plants, it is necessary to pay attention to factors such as the ability of the soil to provide nutrients, determine the nutritional needs that the plants need, from which there are appropriate fertilization methods

Fertilization is to compensate for the amount of mineral nutrients for the soil to help plants absorb more nutrients, develop better, plant roots go deeper, nutrients from deep layers are mobilized more, more biomass and root biomass

were formed Leaving a greater mass of roots and other bioaccumulation in the soil every year, helping to provide more humus to the soil, making the soil more porous, better absorptive capacity and soil fertility Farmers can save more fertilizer not only because nutrients from organic matter are returned to the soil but also because the fertilizer utilization ratio is increased

For effective fertilization, soil properties should be analyzed before application Soils with heavy or light mechanical composition must be given priority to organic fertilizers Applying organic fertilizer for soil with heavy mechanical composition, bury shallowly, while for soil with light mechanical composition, it must be deeply buried and heavy soil can be applied a lot, concentrated fertilizer, while light soil must be fertilized a little , fertilize several times and apply close to the requirements of the plant

Fertilizer for plants should be applied according to the needs of the plant There are plants that need a lot of nitrogen (plants for leaves), there are types that need a lot of potassium (trees for tubers, fruit trees, trees for sugar) Seeds that are fertilized with a lot of phosphorus will have bright seeds, good seed quality, and sown with seeds that have more phosphorus, more vitality, and higher yields Oil crops, legumes, and spices need an adequate supply of sulfur

Each growth stage of each plant also has different requirements The first stage plants need a lot of phosphorus and nitrogen, the later stages need a lot of nitrogen, potassium and trace elements Any stage should not over-fertilize the plant's needs and every stage must provide it nutrients in a balanced manner

Fertilizer for plants, but the growth of plants is directly affected by weather conditions and climate, so it may be necessary to adjust the fertilizer application to suit the weather situation Plants that stop growing in the northeast monsoon should not be fertilized with nitrogen because it can reduce the cold tolerance of the plant, so they may be planning to fertilize but have to step back and sometimes have to fertilize earlier because the tree grows early On sloping

land, fertilizing must be based on weather conditions (rain and wind), sometimes you have to wait for the sky to clear and clear before applying to avoid washing away the fertilizer, but sometimes you also have to wait for the raindrops to dissolve the fertilizer Fertilization to the deep layer of the roots is more favorable

In summary, in agricultural production, the use of fertilizers must aim to maximize the efficiency of fertilizer use, to make plants able to absorb the most nutrients from fertilizers Determining the right type of nutrients, the plant needs

is mentioned first, followed by the amount the plant needs, next is the time the plant needs to provide and one thing that cannot be ignored is how to fertilize it

to ensure the most favorable for the absorption of nutrients by the plant and minimize the loss of nutrients in the manure

From that determination, there will be reasonable fertilization methods The basis of building a reasonable fertilizer regime is based on the nutritional needs of the plant and the supply capacity of the soil At each growth stage, plants need different nutrients with different amounts of fertilizer Therefore, it

is necessary to distribute the amount of nutrients required by the plant in different stages There are two periods that need to be prioritized to feed the tree: the period of crisis and the period of high performance

The crisis period of a nutrient element is the period in which the lack of that element will have the worst effect on growth and yield The period of high yield is the period when the nutrient element has the best effect on yield, the least amount of nutrients is needed for a unit of harvested product, so the fertilizer investment has the highest efficiency In manufacturing, periods of high efficiency do not coincide with times of crisis

2.5.2 Research on fertilizer application for soybean in the world

Besides research on varieties, many studies have been conducted on application of various fertilizers for soybean It is very important to study the

fertilizer regime, planting mode, and care for the plants to grow well and promote the full potential of the variety

Nitrogen requirement is the most important factor for soybean plants The nitrogen requirements of soybean at different growth stages are different However, the nitrogen requirement of soybean is not high because the roots are

in symbiosis with the bacterium Rhizobium japonicum, so the plant has the

ability to fix nitrogen and provide the soil with a large amount of nitrogen

According to Imsande (1992), the most nitrogen crisis stage in soybean is the seed making and firming stage (R5 – R6) Lack of nitrogen at this stage leaves will fall prematurely because nitrogen in the leaves is inherited for seed development The authors Ashour and Thalooth (1983) concluded that foliar nitrogen supplementation at the seed making and firming stage (R5 – R6) has the effect of increasing grain yield and increasing biomass yield

According to Watanabe et al (1986), to achieve a high seed yield (3 tons/ha) soybean needs to accumulate 300 kg N/ha From the results of field experiments, the author showed that applying 60 kg N/ha and 120 kgN/ha at flowering increased soybean yield up to a saturated N content of 180 kg N/ha According to Sinha (1987), Borkert & Sfredo (1994) to achieve high soybean yield, it is necessary to fertilize soybean with a significant amount of N at about

150 kg/ha

Research by Bona et al (1998) on the effect of late N for soybean indicated that adding N fertilizer at the rate of 150 kg/ha at the beginning of the fruiting period for soybean varieties with finite growth behavior has the effect of increased seed yield and harvest coefficient, but has no effect on varieties that grow indefinitely, but only causes the plant to continue vegetative growth

to yield because then N2 fixation was inhibited Excessive nitrogen fertilization

or improper fertilization will inhibit the formation, growth, and activity of nodule bacteria Nitrogen fertilization will not increase soybean yield if soil

However, if the soil is poor in organic matter and poorly drained, nitrogen fertilization with the amount of 50-110 kg/ha has the effect of increasing yield

In addition, phosphate is a very significant factor for soybean When plants are provided with adequate phosphorus, the rate of flower and fruit drop will be reduced, the fruit set rate is increased, the rate of firmness will increase significantly According to Dickson et al (1987), low soil availability of P is the most important factor causing low yield in many Asian countries According to Tiaranan et al (1987), in Thailand, many soybean production areas have easily digestible P content in the soil from 1-5 ppm, when phosphate fertilizer application has doubled yield, the author thinks that the phosphorus crisis of soybean is about 8 ppm

In Australia, Dickson et al (1987) conducted experiments on phosphate fertilization of fields in Queensland and showed that soybean yield was significantly increased when phosphate was applied, the soybean's susceptibility

to secondary phosphorus fertilizers was significantly increased It depends on soil acidity, organic matter content and soil mechanical composition

In Indonesia, fertilizing soil with easily digestible nutrients below 18 ppm has significantly increased soybean yield, lack of easily digestible phosphorus is often associated with soil, and high Al, Fe, and Mn content hinders bio growth and productivity formation (Salesh & Sumarno, 1993)

In acidic soil, the ability to retain phosphorus is often high because the ratio of Fe and Al is high, causing severe phosphorus deficiency, limiting the ability of soybean to absorb nutrients The application of lime will increase soil

pH, thereby increasing the easily digestible phosphorus content to help plants

absorb phosphorus easily In addition, it is necessary to combine N, P and organic fertilizers to improve the efficiency of phosphate fertilizer use

Potassium affects the growth, development, yield and quality of soybean seeds Research by Smit (1998) on the response of soybean to potassium application showed that K application on leaves does not replace K application before planting The author also concluded that the protein content in seeds was negatively correlated with the amount of potassium fertilizer (both KCl and

the amount of K fertilizer applied to the soil

Nigeria (1990-1991) research on the effectiveness of the combination of mineral fertilizers N, P, K has concluded that economic efficiency is highest in the formula 60 tons of manure + 200 kg of N, P, K (15:15:15)/ha and applied during the branching period of soybean

2.5.3 Research on fertilizer application for soybean in Vietnam

With each crop, the nutritional needs of different crops are different When provided with adequate nutrients, crops in general and soybean plants in particular will promote their yield potential In the technical measures of intensive farming to improve soybean yield, fertilizer plays a very important role Therefore, in addition to determining the appropriate set of varieties for each region and each production season, it is necessary to research and perfect the fertilizer application process to improve yield for each variety in each season and different soil conditions necessary power

Nitrogen fertilizer plays an important role in the growth, development and yield of soybean The source of nitrogen for soybeans is from fertilizers, soil and the ability to fix atmospheric nitrogen by nodulation bacteria Each stage of soybean growth requires different amounts of nitrogen Nitrogen is used in the

Nitrogen and phosphorus have the effect of promoting each other in increasing the number of fruiting branches and number of fruits/plant of soybean (Le Dinh Son, 1988) Nguyen Van Bo (2001) also indicated that N fertilizer alone gives an increase by 1.4 quintals/ha, while the same amount of nitrogen on the background with phosphate fertilizer give an increase by 2.3 quintals/ha

Research by Vo Minh Kha (1996) showed that on acidic hill soil, high iron and aluminum content fertilized with phosphorus and nitrogen had the effect of improving soybean yield significantly According to the author, on relatively rich soil, nitrogen fertilization increases yield by 40-50% Nitrogen fertilization is important for maximum yield, however, excessive NO3 application is harmful to yield, so nitrogen fixation is completely inhibited (Ngo The Dan et al., 1999)

According to Vu Dinh Chinh (1998), the combined application of N and P

N/ha increased the number of nodules, the number of firm fruits/tree and seed yield Besides, author Tran Danh Thin (2001) also said that the combination of

N, P, Ca had a clear effect in overcoming the limitations of soil nutrient factors, improving the yield of soybean and groundnut The combination of all three factors N, P, K gives the highest yield in both high and low fertilizer substrates

Soybean plants often absorb phosphorus from fertilizers and until the end

of the crop However, the increase in total P uptake may be limited because the

P in the manure is replaced by P in the soil Phosphorus also increases the ability

to form nodules of soybean High application of P increases the number and volume of nodules This potency depends on the variety, weather conditions, and growth stage of the soybean

When studying the effect of phosphate fertilizer dosage on yield and nitrogen fixation capacity of soybean in the northern midland hills of Vietnam, Tran Van Dien (2001) showed that when increasing the amount of phosphorus fertilizer for soybean, with nodular soybean varieties, there is almost no reaction As for soybean varieties with nodule, it has the effect of increasing the seed yield and leaves significantly Besides, the lack of easily digestible P is often associated with acidic soil with high Fe, Al, and Mn content Research by Nguyen Thi Dan (1996) indicated that phosphorus increases the nitrogen-fixing activity of nodule bacteria Depending on the high or low yield and the mechanical composition available in the soil to determine the appropriate level

of P fertilizer In addition, Nguyen Van Bo (2001) found that on alkaline soil, if phosphate is applied, plants can absorb 120-130 kg of N/ha, while without phosphate fertilizer, plants can only absorb 40-50 kg N/ha

Tran Thi Truong and Tran Thanh Binh (2005) found that the most appropriate ratio of nitrogen, phosphorus and potassium fertilizers for soybean is 1:2:2 Nitrogen and potassium are two factors that have a great influence on yield and give a bountiful 1.4 - 5.4 quintals/ha for nitrogen and 2.6 - 4.3 quintals/ha for potassium If fertilizing potassium separately, it will give a bountiful 1.4 quintals/ha, on the nitrogen base, it will yield 4.3 quintals/ha Separate application of nitrogen only yields 1.4 quintals/ha, on the basis of phosphate 2.3 quintals/ha; on the background with potassium 3.1 quintals/ha; on the background with potassium and phosphorus is 5.4 quintals/ha

Potassium plays an important role in photosynthesis to create sugars and organic matter for plants Insufficient potassium for the plant's needs reduces growth, yield, and susceptibility to pests and diseases Potassium is equally important at all stages of soybean plant growth and it greatly affects the nutritional balance of the plant

The effect of K is often related to P, soybean yield increased when K and

P were applied separately, but the highest yield was achieved when K and P were combined

According to the Ta Kim Binh et al (2000) for study on fertilization for soybean variety DT2000, in the spring crop with the application of 30 kg N: 60

had the highest yield

According to Nguyen Van Lam (2005), in the spring crop, the variety

K2O

CHAPTER III MATERIALS AND METHOD 3.1 Plant materials

Soybean variety VNUAD2 was used for the experiment VNUAD2 was breeding from hybridization of 4904 x VI045032 VNUAD2 was also registered for intellectual property right in 2021

3.2 Location and time

Experiment was in the open field of Faculty of Agronomy, Vietnam

National University of Agriculture in winter season (from Sept 2021 to January

2022)

3.3 Experimental design

Three levels of nitrogen fertilizer and four levels of potassium fertilizer were applied to VNUAD2 Experimental designed was split-plot design with three replications VNUAD2 was planted with density of 50

Nitrogen fertilizer had 3 levels, from 40 – 60 kg/ha:

The experimental setup was as follows:

Protective

strap

Protective strap

Protective strap

3.4 Cultural practices

Soil was prepared carefully and cleaned weeds before sowing

Fertilizer application per ha wasas follows: Song Gianh microbiological

application was applied according to treatment Fertilizer was applied 3 times:

Basal dressing was done after seed bed preparation and before sowing, with the entire amount of microbial fertilizer and phosphorous

First application was done when plants had 2-3 fully expanded leaves, with half of the amount of nitrogen and potassium

Second application was done when plants had 4-6 fully expanded leaves, with the rest of nitrogen and potassium

The field was kept clean of weeds and managed in such a way to ensure uniform plant growth and development The field was also kept moist and checked regularly for insect pests and diseases

3.5 Trait measurements

Traits were evaluated according to QCVN 01-58: 2011/BNNPTNT by Ministry of Agriculture and Rural Development for soybean

3.5.1 Growth and development characters

Measured traits for VNUAD2 are shown in Table 3.1 Measurements were recorded for 3-10 plants/plot and at three different growth stages depending on the traits Various traits were recorded such as plant height (cm), first pod insertion height number of leaves and nodes on main stem, number of primary branches or fresh and dry weigh of root, stem and leaves

Table 3.1 Measured traits for VNUAD2 in winter season 2021

harvest for 10 plants/plot

main stem at harvest for 10 plants/plot

Count the total number of effective nodules; 3 plants/plot and 3 growth stages of initial flowering, full flowering, and podding

Weight the total nodules of each plant; 3 plant/plot and 3 growth stages of initial flowering, full flowering, and podding 8-

dried root, stem and leaf

Collect 3 plants/plot and at 3 growth stages of initial flowering, full flowering, and podding; weight all fresh leaves of each plant and convert to areas as follows::

+ Weight all fresh leaves of each plant;

take average of 3 plants

3.5.2 Yield components and yield

For yield components, measurement was recorded for 10 plants/plot (Table 3.2)

Table 3.2 Yield components and yield measurement for VNUAD2 in winter

season 2021

Count the total number of pods pẻ plant for 10 plants/plot and take average

2

Percentage of filled

Count the number of filled pods for

10 plants/plot; and convert to the percentage to the total number of pod

Count the number of 1-seed pods for 10 plants/plot; and convert to the percentage to the total number

of filled pod

Count the number of 3-seed pods for 10 plants/plot; and convert to the percentage to the total number

of filled pod

Weight 3 samples of 1000 seeds per plot (seed humidity of 12%) and take average

plant/plot and take average

Table 3.3 Evaluation of disease and pest damage and lodging resistance of

soybean

Unit

or score

Evaluating methods & expression

fruit)

Severe (> 25% - 50% infected number of

fruit)

Very severe (>50% infected number of fruit)

Incidence of pod borer = Number of damaged pods / total number of surveyed pods Investigate 15 plants using 5-point

Investigate 15 plants using 5-point angular

method

resistance

Before harvesting

No falling (Almost plants stand straightly)

Low (<25% plants fall down) Medium (25% - 50% plants fall down, other

plants are inclined ≥45%)

High (51 - 75% plants fall down) Very high (>75% plants fall down)

Count the fallen plants in a plot

CHAPTER 4 RESULTS AND DISCUSSION 4.1 Effects of fertilizers on growth of VNUAD2 variety in winter season 2021

ANOVA analysis showed significant differences among fertilizer treatments on growth characters of VNUAD2, including plant height, height of first pod insertion, number of nodes and leaves on the main stem, and number of primary branches (Table 4.1)

Plant height reflects the growth and development of the varieties under the certain conditions, the lodging resistance as well as other yield components The growth of the main stem is greatly influenced by external conditions such as temperature, light, soil and nutritional factors The growth of the main stem is also associated with various quantitative traits such as number of leaves, number

of branches, numbers of effective nodes, number of pods and flower differentiate in plant

In general, plant height increased as level of nitrogen and potassium increased For nitrogen, average of plant height increased from 32.3 cm at N1 to 40.3 cm at N2 For potassium, average of plant height increased from 35.1 cm at K1 to 40.4 cm at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher plant height Combination of N2K3 resulted in highest plant height of 44.6 cm

Height of first insert increased as level of nitrogen and potassium increased For nitrogen, average of height of first insert increased from 11.7 cm

at N1 to 13.2 cm at N2 For potassium, average of height of first insert increased from 11.4 cm at K1 to 13.6 cm at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher height of first insert Combination of N2K3 resulted in highest height of first insert of 14.2 cm

Number of nodes on main stem increased as level of nitrogen and potassium increased For nitrogen, average of number of nodes on main stem increased from 8.9 (nodes/plant) at N1 to 10.7 (nodes/plant) at N2 For potassium, average of number of nodes on main stem increased from 9.1

(nodes/plant) at K1 to 10.4 (nodes/plant) at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher number of nodes on main stem Combination of N2K3 resulted in highest

number of nodes on main stem of 11.2 (nodes/plant)

Table 4.1 Effects of fertilizers on growth of VNUAD2 variety in winter

season 2021

Treatment

Plant height (cm)

Height

of first insert (cm)

Number of nodes on main stem (nodes/plant)

Number of leaves on main stem (leaves/plant)

Number of primary branches(branches)

Number of leaves on main stem increased as level of nitrogen and potassium increased For nitrogen, average of number of leaves on main stem increased from 6.9 (leaves/plant) at N1 to 8.7 (leaves/plant) at N2 For potassium, average of number of leaves on main stem increased from 7.1 (leaves/plant) at K1 to 8.4 (leaves/plant) at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher number of leaves on main stem Combination of N2K3 resulted in highest number of leaves on main stem of 9.2 (leaves/plant)

In general, number of primary branches increased as level of nitrogen and potassium increased For nitrogen, average of number of primary branches increased from 1.6 (branches) at N1 to 2.0 (branches) at N2 For potassium, average of number of primary branches increased from 1.5 (branches) at K1 to 2.1 (branches) at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher number of primary branches Combination of N2K3 resulted in highest number of primary branches

In general, root weight increased as level of nitrogen and potassium increased For nitrogen, average of root weight increased from 1.28 g at N1 to 2.20 g at N2 For potassium, average of root weight increased from 1.17 g at K1

to 2.52 g at K3 However, application of more than 50 kg/ha nitrogen or more

than 100 kg/ha potassium did not result in higher root weight Combination of N2K3 resulted in highest root weight of 3.18 g

Stem weight increased as level of nitrogen and potassium increased For nitrogen, average of stem weight increased from 1.67 g at N1 to 3.06 g at N2 For potassium, average of root weight increased from 1.66 g at K1 to 3.06 g at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher stem weight Combination of N2K3 resulted in highest stem weight of 3.69 g

Leaf weight increased as level of nitrogen and potassium increased For nitrogen, average of leaf weight increased from 3.92 g at N1 to 4.78 g at N2 For potassium, average of leaf weight increased from 3.49 g at K1 to 5.44 g at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher leaf weight Combination of N2K3 resulted in highest leaf weight of 6.34

Table 4.2 Effects of fertilizers on fresh weight of VNUAD2 variety in

winter season 2021 at different growth stages

Leaf weight (g)

Root weight (g)

Stem weight (g)

Leaf weight (g)

Root weight (g)

Stemweight (g)

Leaf weight (g)

In general, root weight increased as level of nitrogen and potassium

increased For nitrogen, average of root weight increased from 1.52 g at N1 to 2.47 g at N2 For potassium, average of root weight increased from 1.16 g at K1

to 2.86 g at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher root weight Combination of N2K3 resulted in highest root weight of 3.50 g

In general, stem weight increased as level of nitrogen and potassium

increased For nitrogen, average of stem weight increased from 8.01 g at N1 to 9.70 g at N2 For potassium, average of root weight increased from 7.63 g at K1

to 10.37 g at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher stem weight Combination of N2K3 resulted in highest stem weight of 11.18 g

Leaf weight increased as level of nitrogen and potassium increased For

nitrogen, average of leaf weight increased from 5.92 g at N1 to 7.56 g at N2 For potassium, average of leaf weight increased from 5.59 g at K1 to 7.83 g at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher leaf weight Combination of N2K3 resulted in highest leaf weight of 8.72 g

In general, root weight increased as level of nitrogen and potassium

increased For nitrogen, average of root weight increased from 1.40 g at N1 to 2.67 g at N2 For potassium, average of root weight increased from 1.51 g at K1

to 2.68 g at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher root weight Combination of N2K3 resulted in highest root weight of 3.75 g

Stem weight increased as level of nitrogen and potassium increased For

nitrogen, average of stem weight increased from 15.08 g at N1 to 18.99 g at N2 For potassium, average of root weight increased from 15.33 g at K1 to 19.05 g at K3 However, application of more than 50 kg/ha nitrogen or more than 100 kg/ha potassium did not result in higher stem weight Combination of N2K3 resulted in highest stem weight of 20.02 g

In general, leaf weight increased as level of nitrogen and potassium

increased For nitrogen, average of leaf weight increased from 6.05 g at N1 to 7.13 g at N2 For potassium, average of leaf weight increased from 5.57 g at K1

to 7.28 g at K3 However, application of more than 50 kg/ha nitrogen or more